/*
 * Copyright 2000-2019 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.ide.projectView;

import com.intellij.openapi.vfs.VirtualFile;
import org.jetbrains.annotations.NotNull;

import java.util.Collection;
import java.util.Collections;
import java.util.Set;

/**
 * Specifies that the element corresponds to several virtual files.
 * For example, a package may correspond to several folders in a project,
 * or a resource bundle may correspond to several properties files.
 */
public interface RootsProvider {
  /**
   * @deprecated use {@link Collections#emptySet()}
   */
  @Deprecated
  Set<VirtualFile> EMPTY_ROOTS = Collections.emptySet();

  /**
   * @return a collection of corresponding virtual files
   */
  @NotNull
  Collection<VirtualFile> getRoots();
}
